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A number of interesting properties have been found in this p-type semiconductor material that have led to its myriad technological applications in important fields including solar energy conversion [2], photocatalysts [3], fuel cells [4], emission control [5] and gas sensing [1].
It can be seen clearly that the inner Cu2O oxide layer is composed of coarse grains whereas the outer CuO oxide layer consists of considerably fine grains.
Under the influence of the stress, the two oxide layers which are composed of many grains will get thicker and thicker.
Through the outward diffusion of Cu ions along the grain boundaries, Cu cations are deposited onto the CuO grains, where CuO grains serve as the structural templates for CuO NWs nucleation.
The out diffusion and deposition of Cu cations lead to the formation of CuO NWs on the CuO grains.

The samples for optical microscopy and scanning electron microscopy (SEM) were etched with a solution of 4 vol% nitric acid + ethyl alcohol The samples were examined in a Philip-505 scanning electron microscope equipped with an energy dispersive X-ray spectrometer (EDX) The grain size was determined using a linear intercept method from a large number of nonoverlapping measurements.
Table 1 Chemical composition of investigated alloys (mass percentage) Results and Discussion Compositions of the Alloys are shown in Table 1, and Fig. 1 shows comparison of the grain of the alloys, it can be seen that the average grain size of investigated alloys significantly increased with the increase of the content of Ce.
The average grain size of AM50, AM50-1.2La, AM50-0.6La-0.6Ce and AM50-1.2Ce are about 650µm, 630µm, 1300µm and 1600µm respectively.
It is not clear why Ce coarsened the grain size of Mg-5Al-0.3Mn-1RE alloys.
Another is the grain size of the alloy containing Ce is more coarse than that of of the alloy containing La.

When the content of Cu exceeded a certain number (0.3 wt.%), the thermal conductivity declined in an increasing range.
Literature research shows that the typical phenomenon which Al-Mg-Si aluminum alloy produced is local pitting corrosion, this pitting corrosion in grain boundary was the most significant.
In the function of the temperature effect, when rich copper phase (Cu2FeAl7, CuAl2) were precipitated on the grain boundaries, poor copper area was generated around grain boundaries, there was corrosion battery between the rich copper area and poor copper area of grain boundaries, poor copper area was the anode, and rich copper area became the cathode, intergranular corrosion occurred between the anode and cathode, so the corrosion resistant performance dropped as Cu element added.
On the other hand, when the cooling intensity was excessive, the rich copper phase more likely generated on grain boundaries, thus after quenching processing, the corrosion resistance property of the alloy is poor (see figure 2).
Secondly, hard phase (Cu2FeAl7 and CuAl2) particles were diffuse distribution in microstructure after aging treatment, they can prevent grain boundary moving on further, pin dislocations motion, which caused strong dispersion strengthened structure[5].

Preferential etching at grain boundaries was evident at higher temperature.
At intermediate temperature as shown in Fig. 1(b), the etched grain boundaries resulted in the initiation of cracking, probably because of insufficient annealing at grain boundaries and relatively higher cooling rate upon the end of irradiation.
Grain boundary etching, dents and in-grain cracking were observed.
In the case of 350 keV O + irradiation effect of implantation became evident at high temperature, therefore the F2g peak position appeared at relatively high wave number.
The surface of CeO2 irradiated with 300 keV Xe + showed preferential etching at grain boundaries and embossed features.

Such conditions lead to a final microstructure after complete solidification made of quasi-equiaxic grains, not dendritic.
The results is the formation of a brittle β- intermetallic phase near the grain boundaries detrimental to mechanical properties, particularly for ductility.
By the use of a MTS 100 monoaxial universal hydraulic testing machine, axial tensile tests and fatigue axial tests (on polished specimens, with fatigue ratio R=0.1 and number of cycles up to 5·106), have been performed for both the un-treated and treated samples.
On one hand, the ductility increased thanks to the interruption of a quite-continuous brittle β-phase network near the grain boundaries and a little grain growing, as secondary effect of the heat treatment.
Furthermore, the reduction of brittle β-phase leaded to increase of UTS, counterbalancing the detrimental effect of grain growth.

The main reasons for scattering attenuation are concerned with many factors, for example frequency of ultrasound, velocity, geometric parameters of object, grain size and elastic anisotropy [5].
It can be observed that the (α+β) microstructure of TC4 alloy consists of the equiaxial αp phase and lamellar secondary αs grains distributed in the matrix of the transformed β phase.
The cooling rate of FC is very slow (1°C/min), the thick lamellar α phase nucleates at the grain boundary and grows throughout the grain internal, the β boundaries are coarse (Fig.2d).
Alpha phase is in close-packed hexagonal structure, the coordination number of it is greater than that of body-centered cubic beta phase.
With the increasing amount and thickness of α phase, the scattering caused by α/α and grain internal interfaces increase.

The source may contain grains of different size, orientation, and polytype.
It can be seen, that the luminescence intensity at 560 nm (Fig. 1b) directly correlates with the grain structure and the polytype.
The sample contains mostly 15R-SiC and 6H-SiC, only few grains are 4H-SiC.
The 15R grains show the highest luminescence intensity and all 6H grains show less luminescence.
The 4H grains are shown in black in the topogram since their emission at 560nm is negligible.

The roughness values measured parallel to grain and perpendicular to grain are summarised in Table 1.
Tab. 1 Basic statistical characteristics for roughness parameters Ra and Rz after various wood surface treatments Basic statistical characteristics Old spruce wood Recent spruce wood Original surface Surface treated with dry ice Milling Surface treated with dry ice Ra Rz Ra Rz Ra Rz Ra Rz Parallel to grain [mm] 13.06 84.48 35.35 280.96 4.25 32.76 21.23 190.95 s [mm] 2.57 13.76 6.88 45.73 1.30 9.971 9.75 69.74 v [%] 19.70 16.30 19.50 16.30 30.60 30.40 45.92 36.50 Perpendicular to grain [mm] 25.50 192.90 41.52 284.09 6.641 58.11 18.81 203.86 s [mm] 3.04 25.53 8.63 64.99 1.53 11.45 7.47 56.89 v [%] 11.90 13.20 20.70 22.90 23.05 19.70 39.70 27.90 basic length l = 8 mm , number of lengths measured n = 30 The roughness values obtained perpendicular to grain were significantly higher than the corresponding values parallel to grain, mainly due to this orientation of wood cell elements.
These depressions were created by dry ice grains hitting the wood surface.
The depressions also compensated differences in roughness between the directions parallel and perpendicular to grain.

The Ag grains in Ag film are formed with roughly 100 nm grain size over all SiC surface.
Hillocks appear on the heated Ag film, grow abnormally as compared with the size of as-deposited Ag grains shown in Fig. 2(a).
When sufficiently high thermal compressive stresses is generated in the Ag film, stress migration causes hillock growth and abnormal grain growth at the interface.
This work was partially supported by Grant-in-Aid for Scientific Research (S), Grant Number 24226017.
Suganuma, Pressureless wafer bonding by turning hillocks into abnormal grain growths in Ag films, Appl.

Resistance to wear decreased with the increase in crystalline grain size, similar to hardness values.
It is also observed that the glassy region is smaller and the number of crystallites is greater than that of the sample shown in Fig. 1.
This indicates that the cooling in the furnace after the crystallization heat treatment causes grain growth due to the longer heat treatment.
Since the hardness values decreased due to grain growth[5], this result is expected.
Similar to microhardness results, grain growth decreases the resistance to wear.